Rank Caches
When you run a mapping that uses a Rank transformation, the Data Integration Service creates an index cache and data cache in memory to run the transformation. If the Data Integration Service requires more space than available in the memory cache, it stores overflow data in cache files.
When you run a mapping that uses a Rank transformation, the Data Integration Service compares an input row with rows in the data cache. If the input row out-ranks a cached row, the Data Integration Service replaces the cached row with the input row. If you configure the Rank transformation to group rows, the Data Integration Service ranks rows within each group.
The Data Integration Service creates the following caches for the Rank transformation:
- •Index cache that stores group values as configured in the group by ports.
- •Data cache that stores information based on the group by ports.